What the Attendance Percentage Calculator does
This calculator works out attendance as a percentage of working days, and - more usefully - how many of the days you have left you still have to attend to reach a target. It does both for a single month or for a whole term or year, with each period shown separately and cumulatively.
The arithmetic is trivial. The part that actually decides the answer is the denominator: whether a day of certified sick leave is counted as attended, removed from the count altogether, or treated as an absence. Every policy answers that differently, so this page makes you state it, shows the treatment next to each leave type, and reports the counted days as well as the percentage - so anyone reading the figure can see how it was reached.
How to use it
- List your periods, one per line, as
label, working days, days present. A term with three months is three lines; a single month is one. Half days are allowed. - Add each kind of leave and choose how your policy treats it: counted as present, excluded from the working days, or counted as absent.
- Enter the attendance target and the number of working days still to come.
- Read the headline percentage, then the days you still need to attend - and whether the target can still be reached at all.
- Download the CSV or print the breakdown if you need to attach it to a claim, an appeal or a review.
Reading the results
The headline percentage is counted present divided by counted working days. Both numbers are shown, because a percentage without its denominator cannot be checked.
"Days needed" is rounded up. Half a day never reaches a threshold, so if the arithmetic says 4.5 days you need 5.
"Target unreachable" means that attending every remaining day still falls short. That is worth knowing early: at that point the conversation is about excluding days, not about attendance.
Cumulative percentage is the figure most institutions and employers actually act on, because a bad month can be carried by a good one - or not.
Worked example: a three-month term at a 75% requirement
A student has 21, 20 and 22 working days across January, February and March - 63 in total - and attended 19, 20 and 17 of them, so 56 days present. Three days of certified sick leave are excluded under the policy, and two days of unapproved absence are counted as absent.
Excluding the three certified days leaves a denominator of 60. The numerator is the 56 days present, so attendance is 56/60 = 93.33%. Had the three sick days not been excluded, it would have been 56/63 = 88.89% - a difference of four and a half points from one policy clause.
With 20 working days still to come, the final denominator is 80 and 75% of 80 is 60 days. With 56 already counted, four more days are needed, which means 16 of the remaining 20 can be missed. Attending all 20 would finish at 76/80 = 95%.
Formulas and scoring rules
- Counted working days
denominator = working days - days of leave your policy excludes- Counted as present
numerator = days present + days of leave your policy credits- Attendance
percentage = numerator / denominator x 100Not rounded internally; shown to two decimals.- Days still needed
needed = ceil(target/100 x (denominator + remaining) - numerator)Clamped to zero. If it is larger than the days remaining, the target cannot be reached.- Days you can still miss
canMiss = remaining - needed- Best and worst possible
best = (numerator + remaining) / (denominator + remaining); worst = numerator / (denominator + remaining)
Why two people get two different percentages from the same register
Almost every argument about an attendance figure is an argument about the denominator. Suppose 22 working days, 18 attended, and 4 days of authorised absence. Counting the authorised days as attended gives 100%. Excluding them gives 18/18 = 100% as well. Counting them as absent gives 18/22 = 81.8%. Same register, three answers, and all three appear in real policies.
That is why this page will not pick for you. Each leave type carries its treatment, the counted days appear next to the percentage, and the CSV carries both - so the figure can be reproduced by whoever has to sign it off.
Forecasting honestly
A forecast is only meaningful if the number of remaining working days is real. Use the actual days left in the term, roster or contract period, not the days left in the calendar. If the remaining days themselves might be excluded later - a planned medical absence, for instance - the forecast will move, and it is better to say so than to present a single reassuring number.
Rounding up matters here. A calculator that says "4.5 days" invites someone to attend four and miss the target by a fraction of a point. This one says five.
Limitations: what the result does not prove
- It does not know your policy. Which leave counts, whether half days exist, whether a late arrival is a partial absence and whether there is an appeals route are all decided by your employer, school or institution.
- It does not read a register, a biometric log or a timesheet. The days you type in are the days it uses.
- Attendance thresholds often carry consequences - exam eligibility, probation, pay - that depend on rules this page knows nothing about. Check the figure with whoever administers it before relying on it.
- The forecast assumes the remaining working days are counted in the denominator. If some are later excluded, both the target and the days needed change.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- ISO 8601-1 - Date and time: basic rules - checked 19 Sep 2026
Frequently asked questions
How do I calculate attendance percentage?
Divide the days counted as present by the working days counted, then multiply by 100. The difficulty is deciding which days are counted on each side of that division, which is a policy question rather than an arithmetic one - so this calculator asks you to state the treatment of each kind of leave.
How many days can I miss and still have 75% attendance?
It depends on how many working days remain, because every remaining day adds to the denominator. Enter the days still to come and the calculator gives both the days you must attend and the days you can still miss, rounding the requirement up because a fraction of a day never reaches a threshold.
Does authorised or medical leave count as attendance?
Only if your policy says so. Three treatments are common: credited as attended, excluded from the working-day count entirely, or counted as an absence. All three are offered here, and the counted days are shown alongside the percentage so the choice is visible.
Why does excluding leave raise my percentage so much?
Excluding a day removes it from the denominator, so the remaining days each carry more weight. Ten excluded days out of a hundred turn 80/100 into 80/90, which is 88.9% rather than 80%. The calculator warns you when more than a quarter of the period has been excluded.
Can I use half days?
Yes. Working days, days present and leave days all accept decimals, so a half-day absence is 0.5. Days needed for a target are still rounded up to whole days, because attending half a day does not usually count as attending.
What does it mean when the target cannot be reached?
It means that even attending every remaining working day leaves you below the threshold, because the days already missed are too large a share of the final total. The calculator shows the best percentage still possible so you know exactly how far short it lands.
Is my attendance data sent anywhere?
No. The whole calculation runs in your browser, nothing is uploaded, and no record is stored. You can check that yourself in the network tab of your browser's developer tools - there are no requests while you type.
Last reviewed by the A2Z.Tools team against the sources listed above.
